1. Field of the Invention
This application relates to a method for treating large flowing water bodies, such as rivers, or the like, more particularly to a method for reducing the thickness of the sludge covering the floor of a river or the like.
2. Description of the Related Art
Flowing water bodies, such as rivers, seas, etc., usually have the floors thereof covered with sludge that primarily contain organic substances. When the thickness of the sludge increases to a considerable extent, it can affect the sailing and transporting characteristics, the water holding capacity, and the quality of water of a river. Typical methods available in the art for reducing the thickness of the sludge generally comprise excavation, and/or chemical treatments. The excavation methods are costly and laborious, and the chemical treatments generally employ chlorine and ozone which can result in destruction to the ecology of aquatic animals and plants.
U.S. Pat. No. 5,549,828 discloses a method and apparatus for in situ water purification including sludge reduction via biofiltration and aeration. In this method, sludge reduction is conducted by extending a conduit to the bottom of a water body to draw the sludge into a vertical conduit and then bring the sludge into contact by a pumping system, with bacterial cultures preactivated to optimize enzyme production for sludge solubilization.
U.S. Pat. No. 5,893,978 discloses a method for purifying a lake/marsh into which a river flows. The method as disclosed is limited to the purification of water present in an area near the mouth of the river connected to the lake/marsh in order to purify the water entering the lake/marsh. This patent teaches the use of a purifier or filter floating in a water treating area or fixed at the bottom of the river in the water treating area to remove pollutants, such as eutrophic materials within the water. However, nothing disclosed therein suggests that removal of the eutrophic materials from the surface of a water body can reduce the thickness of sediments or sludge deposited on the floor below the water body.